| The Pinghe graphite deposit and Jianshan graphite deposit locate at the thrust belt of Mingcangshan basement,the thrust belt of Micangshan-Dabashan basement,upper Yangtze Blocks and Yangtze Blocks.And belong to the metall ogenic belt of Longmen mountain-Dabashan mountain.They are very important representative of sendimentary mentamorphic type of graphite deposit,and are important graphite deposits in Sichuan Province.Through the geochemistry test,carbon isotope analysis,SHRIMP zircon U-Pb dating analysis of the graphite deposit,aims to explore deposit geological features,geochemical features and genesis analysis of Pinghe graphite deposit and Jianshan graphite deposit in Nanjiang County,Sichuang Province.And we know:(1)The graphite mineral occurrence in the Mawozi group of Huodiya group,and ore bodies are bedded and lenticular of Pinghe graphite deposit and Jianshan graphite deposit.The ore type are graphite-bearing breccia,graphite schist and graphite-bearing dolomotic marble,and the fixed carbon contene is average of 8.40%,the scales of graphite mineral are less than 0.1mm,of Jianshan graphite deposit.The ore type are graphite schist and graphite-bearing dolomotic marble of Pinghe graphite deposit,the fixed carbon contene is average of 16.32%,the scales of graphite mineral are average of 0.05mm?0.5mm.(2)The restore result of main elements,the metamorphic rock series are clay to dolomite mixture and mud to calcareous sediments,the average is-17.42‰ of ?13C of Jianshan graphite deposit.The metamorphic rock series are mudstone to siltstone and dolomite,the SHRIMP U-Pb age was 751.6±4.5Ma,the average is-24.17‰ of ?13C of Pinghe graphite deposit.Indicating the causes of graphite is the organic carbon and Small inorganic carbon.(3)It was a belt of the Yangtze plate northern margin in the Proterozoic of the graphite deposit area.There are a lot of primitive single-cell organisms and the organics of their metabolism-producing in the coastal and shallow Marine sedimentary areas,and which was carried to the deposit area by ocean,and those are main source of carbon.In addition,there was much of volcanic eruptions at the bottom of the sea,and it produced large amounts of CO2 and HS,and which was carried to the deposit area by ocean.And a lot of CO 2 is reduced in the organic mud sandstone and magnesium carbonate rocks,this is a secondary source of carbon.The strata have strong fold and deterioration in this area,and graphite formation is formed in the regional metamorphism with the Yangzi platform was continuously proliferating and Jinning movement in the neoproterozoic.The graphite scale increases,because of the heat of the magmatic intrusion of Jinning period and chengjiang period.So,we known the Jianshan graphite deposit and the Pinghe graphite deposit genetic are regional metamorphism and the contact metamorphism. |
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